Integrated circuit devices must typically be powered up when operation is initiated. During power-up of an integrated circuit, certain operational parameters must generally be maintained and managed if the integrated circuit is to operate properly after power-up. Power-up can typically involve application of a voltage V.sub.DD to the circuit.
One special type of circuit is a double data rate (DDR) synchronous DRAM. Synchronous DRAMs are described generally in U.S. Pat. Nos. 5,751,656, 5,749,086, 5,666,321, and 5,544,124, assigned to the assignee of this disclosure, and incorporated by reference herein. Typically with such devices, it is desirable to maintain the control pin CKE at a first value during application of a voltage, V.sub.DD, to the circuit. After the circuit has stabilized, and a number of conditions have been met for a period of time, typically 200 microseconds, then CKE must be taken to an input above its first value (e.g. 2 volts). If CKE is taken to an input above its first value prior to the allotted time, circuit operations downstream of power-up can be affected.
One typical prior art way of achieving a desired delay before moving CKE to its desired input, is illustrated by the high level circuit diagram shown in FIG. 1 generally at 20. Circuit 20 includes a delay network 22. Delay network 22, in the past, has comprised first and second RC networks 24, 26, respectively. Essentially, delay network 22 powers-up in accordance with a predetermined delay which is appropriate for enabling certain conditions to be met, e.g. stable power, stable clock, and no operation conditions. A CKE input buffer 28 is provided whose output, CKE, can be taken to its desired voltage after the delay of delay network 22 has been achieved. There are, however, problems associated with the use of a delay network such as delay network 22. Such networks can be unpredictable insofar as performance of the individual RC networks 24, 26, respectively. Specifically, if the delay, for whatever reason, is not adequately long enough, then power-up can be prematurely set off which has downstream implications insofar as circuit operation is concerned.
Accordingly, this invention arose out of concerns associated with providing improved power-up controllers and circuitry, as well as improved power-up methods for integrated circuitry. In particular, this invention arose out of concerns associated with providing improved power-up controllers and circuitry, as well as improved power-up methods for use in connection with dynamic random access memory circuitry.